This invention relates to a process whereby acid and particulate matter can be extracted from air emissions.
In air combustion of hydrocarbons, including fossil fuels, waste oils, and organic debris, residual air emissions are deliberately maintained at a temperature well above the dew point of acids that may be formed during combustion. This temperature is maintained to prevent the condensation of acids on the air handling containment equipment, which condensation would ultimately lead to the corrosion of this equipment. This corrosion is caused by direct acid condensation and by pinhole leaks within the membranes of the metals that constitute the stacks, ducts, fans, scrubbers, and vents of the handling and containment equipment. In the case of pin hole leaks, cooler outside air is drawn into the negative pressure air exhaust passage, which causes acids to condense on the site of the pin hole leak and corrode the membranes, which leads to larger leaks. The same problem occurs as the stack gases are cooled during discharge, which may be done to recover heat energy or to capture and remove toxic metals such as mercury from the gas stream or other particulate matters such as unburned carbon and hydrocarbon compounds. In these instances, the acid will condense on the conduit, which likewise leads to the corrosion of the stack or chimney apparatus. A further complication of these problems is the deliberate under-combustion of fuels or organic debris in order to preclude the formation of nitrogen oxides. Combustion burner temperatures and burn duration are suppressed below the point of optimum combustion due to the inability to mitigate the impact of these acids on the equipment and the environment. These problems remain largely unsolved.
In general the present invention provides an air treatment system comprising an exhaust including an exhaust annulus defined by an inner exhaust wall, an outer exhaust wall circumscribing the inner wall, and a pressurized annulus between the inner and outer walls, and at least one condenser suspended within the exhaust annulus, where the at least one condenser includes a cooling fluid therein.
The present invention also includes a process for treating air emissions comprising directing combustion gases into an exhaust, where the exhaust includes an exhaust annulus defined by an inner wall, an outer wall circumscribing the inner wall, and a pressurized annulus between the inner wall and the outer wall, directing the combustion gases through at least one condenser, where the at least one condenser is suspended within the exhaust annulus, and where the at least one condenser includes a cooling fluid therein, thereby condenses compounds included within the combustion gases to condense into a condensate, collecting the condensate within the exhaust, and directing the condensate out of the exhaust.
Advantageously, the present invention overcomes the problems associated with the prior art by providing an exhaust condenser that deliberately cools exhaust gases and thereby condenses materials, such as acids, within the exhaust stream. These materials can then be captured and collected or further processed. As a result, the use of the exhaust condenser of this invention advantageously allows for the use or recycling of materials that would otherwise be discharged to the environment such as in the form of acid rain. Also, the exhaust condenser provides a means whereby heat energy form exhaust gases can be recovered.